This invention relates to surgical cutting instruments and in particular rongeurs and the like with replaceable cutting tips.
Rongeurs have been used for many years as surgical cutting implements, particularly to cut bone. To be so used, at least one of the jaws of a rongeur must have a very fine cutting edge. In the course of a surgical procedure, however, the jaws can become dull making the implement therefore no longer usable. A dulled cutting edge can cause a portion of the instrument to buckle thereby destroying the instrument. Moreover a dulled instrument is a danger to the patient for several reasons. For example, a dull instrument can cause tissue tearing and it can cause an increase in the operating time both of which can result in increased blood loss and further expense to the patient.
It is conventional practice to either have the cutting edges sharpened or dispose of such implements with dulled edges. In either case great expense is incurred. The cutting edges can typically be sharpened only four times before the jaws no longer meet properly in which case the instrument must be replaced. Currently replacement cost for a single instrument is $500 to $600 dollars, and the useful life of such an instrument is only one to one and one-half years. Since it is customary to use three to four different size rongeurs during a single operation, replacement of an entire set is a significant expense.
Heretofore, an economically practical disposable cutting edge for such implements to make them readily reusable has not been available. This invention presents an economically attractive alternative which makes such implements readily reusable but at a cost much less than is typically required to resharpen them.
Wright U.S. Pat. No. 4,777,948 presents a pistol-like rongeur with a fixed hollow barrel with a slidable rod therein. A forward end of the rod extends beyond the barrel and is up-turned to provide a distal jaw, i.e., a shoulder to oppose a proximal jaw which is a replaceable tube, basically an extension of the barrel. The forward edge of the tube is a cutting edge. The rearmost portion of the tube is clamped to the end of the barrel by a chuck-like device comprising threaded fingers which can be increasingly tightened together by a frusto-conical nut.
Townsend U.S. Pat. No. 4,201,213 presents another barrel and rod in slidable arrangement. In this case, however, the rod is fixed and the barrel is slidable. The forward end of the rod is once again angularly up-turned to form a distal jaw, but this one has an inward facing cutting edge. Opposing that is an outwardly facing cutting edge on an "insert" 16. The inventor describes the insert as not being necessary but is there to "provide additional surface area to the jaw for increased strength . . . " (Col. 3, lines 44-59).
Banko U.S. Pat. No. 4,368,734 presents another surgical instrument but this one is used to perform operations on eyes. It has a fixed outer member 18 with a down-turned end to act as a pointed distal jaw. It also has an inner tube disposed within the outer member, the forward edge of which is the cutting edge of a proximal jaw. Both appear to be replaceable.
Niederer U.S. Pat. No. 3,902,498 presents another surgical instrument similar at its operational tip to the Wright device. It has a fixed barrel with a slidable rod disposed therein. The slidable rod has an up-turned forward end to function as a distal jaw which opposes a circular cutting edge at the forward end of the barrel. As in the Wright patent, the forward end of the barrel, that is the cutting piece, is essentially an extension of the barrel. The cutting piece is replaceable but the inner rod does not appear to be disposable.
Woodward U.S. Pat. No. 460,903 presents a fruit picker. It has a fixed flat bar with two opposed laterally inward slots such that the end of the bar appears to be arrowhead-shaped. The stem of the fruit being picked is inserted into one of these slots. A superior blade with a forward cutting edge slides axially upon the fixed bar to shear the stem. An inferior blade with a blunt forward edge moves with the shearing blade to press the stem against a shoulder formed by the fixed bar. Thus, the device not only shears the fruit from its stem, but continues to grasp the sheared fruit by the cut stem.
Other advantages and attributes of this invention will be hereinafter discussed or will be readily discernible from a reading of the text hereinafter.